1. Field of the Invention
The present invention relates to an apparatus for exchanging workpieces of a machine tool.
2. Description of the Related Art
In conventional machine tools, techniques for exchanging workpieces by moving a workpiece transport means such as headstocks, loader hands, or robotic hands are known. For example, in the case of a vertical lathe, as shown in FIG. 16, one cycle of an exchange of workpieces is given by the following process: when machining is finished, a headstock 51 moves from the machining section to a position above a conveyer 52. The headstock 51 moves down and a chuck 53 puts down the finished work piece WA on the conveyer 52. The headstock 51 moves up and waits above the conveyer 52. The conveyer 52 carries the finished workpiece WA away and delivers an unfinished workpiece WB. The headstock 51 moves down again and the chuck 53 grasps the unfinished workpiece WB. The headstock 51 moves up and then moves to the processing section, thus terminating the cycle.
In conventional vertical lathes, the exchange of workpieces is done by the movement of the headstock 51. So that the headstock 51 is required to reciprocate twice per cycle in a vertical Z-axis direction and the headstock 51 is also required to wait while the conveyer 52 is running. Accordingly, there is the problem that it takes a long time to exchange workpieces.
Therefore, it is a purpose of the present invention to provide an apparatus for exchanging workpieces of a machine tool that reduces the time required for exchanging workpieces, by cutting down the moving distance and the waiting time of a workpiece transport means to a minimum.
In order to solve these problems an apparatus for exchanging workpieces in accordance with a first aspect of the present invention includes a conveyer for conveying workpieces; a transport means for transporting the workpieces between a machining section and a place near the conveyer; a waiting station where unfinished workpieces wait near a conveyer; a first transferring system for transferring unfinished workpieces from the conveyer to the waiting station; a second transferring system for transferring finished workpieces from the transport means to the conveyer; and a third transferring system for transferring unfinished workpieces from the waiting station to the transport means.
An apparatus for exchanging workpieces in accordance with a second aspect of the present invention includes a conveyer for conveying workpieces horizontally in a first axis direction; a transport means for transporting workpieces between a machining section and a place near the conveyer by a horizontal movement in a second axis direction that intersects with the horizontal first axis direction; a waiting station where unfinished workpieces wait next to the conveyer at a position on the second axis; a first transferring system for transferring unfinished workpieces from a position on the second axis of the conveyer to the waiting station; a second transferring system for receiving finished workpieces from the transport means at a position above the waiting station by a movement within a vertical plane including the second axis, and transferring the workpieces to the conveyer; and a third transferring system for transferring unfinished workpieces from the waiting station to the transport means by a vertical movement.
An apparatus for exchanging workpieces in accordance with a third aspect of the present invention includes a conveyer for conveying workpieces horizontally in the first axis direction; a transport means for transporting workpieces between a machining section and a place near the conveyer by a horizontal movement in a second axis direction that intersects the horizontal first axis direction; a waiting station where unfinished workpieces wait next to a conveyer at a position on the second axis; a first transferring system transferring unfinished workpieces from a position on the second axis of the conveyer to the waiting station; a second transferring system receiving finished workpieces from the transport means by a vertical movement above the conveyer, and transferring the workpieces to the conveyer, at an intersection of the first axis and the second axis; and a third transferring system transferring unfinished workpieces from the waiting station to the transport means by a vertical movement.
In accordance with a fourth aspect of the present invention, in an apparatus for exchanging workpieces as in any of the first to third aspects, the transport means is a headstock of a machine tool having, at its lower part, a chuck that is able to hold workpieces.